1. Field of the Invention
The present invention relates to a lens device.
2. Description of the Related Art
There are phase-difference AF (autofocus), contrast AF, and the like as the autofocus of a camera. In phase-difference AF, light entering from a lens is split into two or three or more light components by pupil splitting and is led to a phase-difference AF sensor, and a focusing direction and a focus-shift amount are determined on the basis of a position-shift direction and a position-shift amount of each pupil-split image in a pupil-split direction. As the contrast AF, there are a method of performing focusing by detecting a position where contrast is large while moving a focus lens on the basis of an image taken by an image pick-up element, and a method of picking up the image of a subject by two image pick-up elements disposed at positions having different optical path lengths and performing focusing on the basis of image signals obtained from the respective image pick-up elements (optical-path-length-difference AF). There is also a case in which optical-path-length-difference AF and phase-difference AF are used together (JP07-43605A).